test('two plus two is four',()=>{
   expect(2+2).toBe(2+2);
});

test('null toBe null',()=>{
    expect(null).toBe(null);
});


test('NaN toBe NaN',()=>{
    expect(NaN).toBe(NaN);
});

test('0 toBe false',()=>{
    expect(0).toBe(false);
});

test('null toBe undefined',()=>{
    expect(null).toBe(undefined);
});


test('[] toBe []',()=>{
    expect([]).toBe([]);
});


test('Object-两个独立的空对象',()=>{
    expect({}).toBe({});
});

let a=b={};
test('Object-相同引用地址的对象',()=>{
    expect(a).toBe(b);
});

test('Function-两个独立的空函数',()=>{
    expect(function(){}).toBe(function(){});
});


test('RegExp-两个内容相同独立的正则',()=>{
    expect(/\w/).toBe(/\w/);
});